Utility Meter Battery Charge Estimation Using Current and Voltage
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Solution Overview
Problem
Existing methods for estimating battery charge level in utility meters are inaccurate due to deviations in actual battery capacity, consumption rate, and temperature, leading to potential power loss and unnecessary battery replacement.
Innovation Solution
A meter that determines battery charge level by capturing electrical measurements at multiple instants to calculate accumulated energy consumption, using series resistors and voltage dividers to accurately measure current and voltage, and displays the charge level based on these calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If battery charge level is estimated using nominal storage capacity, nominal consumption rate, and accumulated operating time, then the estimation method is simple, but the accuracy of battery charge level indication deteriorates
Solution Approach 1:
The patent replaces the mechanical/time-based estimation method (using nominal capacity, nominal consumption rate, and accumulated operating time) with an electrical measurement-based method. The microprocessor measures actual current and voltage across the battery at multiple instants, calculates actual energy consumption from these electrical parameters, and determines charge level based on actual rather than nominal values, thereby substituting direct electrical measurement for indirect time-based estimation.
Solution Approach 2:
The patent implements feedback by continuously measuring actual current and voltage across the battery during operation, using these measurements to calculate actual energy consumption, and updating the charge level indication based on this real-time feedback. This closed-loop approach allows the system to adapt to actual battery performance and consumption patterns rather than relying on predetermined nominal values.
2Reliability
If battery charge level is estimated conservatively by adjusting the estimate by a predetermined factor, then the risk of power loss is reduced, but battery replacement occurs prematurely reducing productivity
Solution Approach 1:
The patent enables the battery monitoring system to serve itself by directly measuring its own operational parameters (current and voltage) and calculating its own charge level based on actual energy consumption. This self-measurement approach eliminates the need for conservative external adjustments, allowing the system to determine the true charge level accurately and notify users only when actual replacement is needed, optimizing both reliability and productivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Provides a more accurate indication of battery charge level, reducing the risk of power loss and unnecessary battery replacement, while optimizing battery usage.
Implementation Method 1
measuring a value of a voltage across the series resistor and to determine the value of the current supplied by the battery based on the measured value of the voltage across the series resistor and the known resistance of the series resistor
Implementation Method 2
the voltage divider includes a first resistor and a second resistor, wherein the first and second resistors are connected in series, and wherein the first and second resistors have known resistance values or a known ratio of resistance values
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A meter (2) for measuring the consumption of a utility such as electricity, a fluid, gas, water, or heat, comprises a battery (6) and electronic circuitry (8), wherein the meter is configured so that the battery provides power to the electronic circuitry during a use period, and wherein the electronic circuitry is configured to, for each measurement instant of a plurality of measurement instants during the use period: capture or generate a time value corresponding to the measurement instant; perform one or more electrical measurements on the electronic circuitry at the measurement instant; determine a value of a current supplied by the battery at the measurement instant from the one or more electrical measurements; and determine a value of a voltage across the battery at the measurement instant from the one or more electrical measurements. The electronic circuitry is further configured to use the plurality of time values, the plurality of corresponding determined values of the current supplied by the battery, and the plurality of corresponding determined values of the voltage across the battery to determine an accumulated energy consumption value; determine a battery charge level based at least in part on the determined accumulated energy consumption value; and display an indication of the determined battery charge level.